Sequence of phase correction in multiconjugate adaptive optics

Abstract

The way in which the sequence of phase correction impinges on performance in multiconjugate adaptive optics systems is described. When multiple phase modulators with different conjugate ranges are used, the conjugate images of the phase modulators in the atmosphere must be reimaged in the reverse order post focus, and adaptive phase correction applied in this sequence for perfect amplitude and phase cancellation. Performing the correction without relay optics results in residual amplitude and phase aberrations. It is shown, by Monte Carlo simulations of Fresnel propagation, that the effects of wave optical propagation become nonnegligible at visible wavelengths and for large air masses.

Multiconjugation Optical Relay for an Off‐Axis Solar Telescope

“…How good must the collimation be for an MCAO system? Considering that a solar MCAO system is operating in the visible, should the DMs conjugate images of the turbulence layers be imaged in reverse order postfocus, as discussed by (Flicker 2001), to guarantee optimal MCAO performance? Considering that turbulent layers vary in altitude, a system that images selectable atmospherics layers, as discussed by (Pazder 1996), is a feature that should be considered.…”

“…The decision as to how many DMs will actually be needed, at what conjugate heights to place them, and the order of the layer correction (i.e., the order of DMs as discussed by Flicker [2001]) cannot yet be made, since the site survey is still in progress and information about the structure parameter for refractive index variations Cn2(h) is not available. Further input into the final design will come from the experience gained from the MCAO implementation planned for the Dunn Solar Telescope (Moretto et al 2004;Langlois et al 2004a).…”

The multi-conjugate adaptive optics system of the New Solar Telescope at Big Bear Solar Observatory

“…5 This was supported by Monte-Carlo simulations. 6 However, the impact of using the wrong sequence in this work seems little. Currently, a Zemax analysis is performed at the Instituto de Astrofísica de Canarias (IAC) in the context of the EST study.…”

Simulation of MCAO on (extremely) large telescopes

“…In case Fresnel propagation is done, one can also propagate the shape of the DM shape to it's conjugation altitude. See [33] for more details on the order of conjugation of DMs in MCAO.…”